The invention provides a method for re-circulating combustion of flue gas of a pulverized coal fired boiler, belongs to a method for circulating combustion of oxygen gas (O2) and carbon dioxide (CO2) of pulverized coal, and aims to solve the problems of low heat efficiency and poor burn-out property existing in the conventional combustion method. The method comprises the steps of: 1,igniting and combusting: conveying the pulverized coal to a furnace hearth by using the circulation flue gas, and simultaneously conveying O2 to the furnace hearth for ignition; 2, circulating the flue gas: dividing the high-temperature flue gas generated by combustion into two parts, and performing cooling, dust removal and desulfurization compression on the first part to obtain liquid CO2; dividing the second part into two paths, conveying the first path to an entrance of the furnace hearth by using a high-temperature circulation fan, and mixing the first path of the flue gas and O2; and performing cooling, dust removal and desulfurization on the second path, and conveying the second path carrying the pulverized coal to the furnace hearth by using a cold circulation fan. The method has the advantages of adjusting the steam temperature of the boiler by using the high-temperature flue gas, enhancing convective heat transfer, increasing the steam temperature of the boiler, improving the heat efficiency of the boiler and the denitration rate, increasing the CO2 content after the high-temperature flue gas is cooled, reducing emission load of NOx, lowering CO2 capturing and collecting cost, and meeting the national energy conservation and environmental protection standard.